Propeller

ABSTRACT

An improved propeller design is provided herein. One embodiment includes a propeller with a housing having a diameter sufficient to encloses at least a portion of the propeller blades. The housing may be secured to the ends of the propeller blades. The housing may include a forward facing edge that is flared outwardly. In addition, the housing generally tapers inward aft of the propeller blades reducing the diameter of the housing to form a general funnel shape. In one embodiment, the housing has a rear portion with a substantially constant diameter located aft of the end of the tapered section. Outer blades may be secured to the outer portion of the housing. These outer blades may be useful to, for example, provide additional rear thrust when the boat is shifted into reverse.

RELATED APPLICATIONS

This application claims priority to, and any other benefit of U.S. Provisional Application Ser. No. 60/937,895, titled Improved Propeller, filed on Jun. 29, 2007. The entire disclosure of said provisional applications is hereby incorporated by reference in its entirety.

This invention relates generally to power boats and more particularly to an improved propeller for power boats.

BACKGROUND

Conventional propellers typically include three or more blades and have been used to propel boats through the water for many years. However, conventional propellers are inefficient and typical propellers have a slip of around 45%.

SUMMARY

An improved propeller design is provided herein. One embodiment includes a propeller with a housing having a diameter sufficient to encloses at least a portion of the propeller blades. The housing may be secured to the ends of the propeller blades. The housing may include a forward facing edge that is flared outwardly. In addition, the housing generally tapers inward aft of the propeller blades reducing the diameter of the housing to form a general funnel shape. In one embodiment, the housing has a rear portion with a substantially constant diameter located aft of the end of the tapered section.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a prospective view of an embodiment of a propeller;

FIG. 2 is a side perspective view of the propeller of FIG. 1;

FIG. 3 is a rear perspective view of the propeller of FIG. 1;

FIG. 4 is a side view of a propeller;

FIG. 5 is a side view of propeller in the forward direction showing water and compressed air flow;

FIG. 6 is a side view of propeller in the reverse direction showing water a flow; and

FIG. 7 is an impeller having an attached housing;

FIG. 8 is a prospective view of another embodiment of a propeller.

DETAILED DESCRIPTION

FIG. 1 illustrates an exemplary embodiment of an improved propeller 100. The improved propeller 100 includes a inner propeller 110 having a plurality of blades 115. Secured to the propeller 110 is a housing 120. Housing 120 includes a flared out forward edge 130, a longitudinal housing portion 125, a tapered portion 140, a rear portion 150 and a plurality of outer blades 160. Tapered portion 140 may have a linear taper, as shown, a curved taper, or have any number of different shaped tapers that server to reduce the housing 120 from a first diameter to a second smaller diameter. Propeller 110 includes a forward hub 170 for fitting into a conventional outboard drive unit (not shown). The housing 120 and propeller 110 may have a unitary construction to form improved propeller 100. Unitary construction, as used herein, does not mean it is formed of one solid piece, bur rather may be formed of multiple pieces that are joined or fastened together. Improved propeller 110 may be formed from aluminum, stainless steel, plastic, a composite, combinations of these materials, or any other suitable material(s). In one embodiment the propeller 110 is a conventional propeller, and housing 120 is modified so that it can be secured to the conventional propeller. For example, housing 120 may include pockets (not shown) for receiving blades of a conventional propeller, housing 120 may be mechanically fastened or welded to the conventional propellers. Slight modifications to the conventional propeller for securing it to the housing 110 is contemplated. Outer blades 160 are secured to rear portion 150. Rear portion 150 may flare outward, have a constant diameter, or even taper inward. When the boat is shifted into reverse, housing 120 prevents some of the water that would normally flow over propeller 110 from contacting blades 115. Outer blades 160 provide one means of creating additional thrust in the reverse direction.

In operation, water enters the front of the housing 120. The flared out forward flange 130 causes more water to contact the blades 115 of propeller 110 than would normally contact the blades 115. As the propeller 110 turns, water is forced though the reduced portion of housing 120. As the water travels through the housing 120, it reaches the tapered portion 140. Because water does not compress, the water is accelerated as it passes through the housing 120 and out the rear portion 150. With the improved propeller 100, all of the accelerated water is focused rearward verses with a conventional propeller where some of the water is directed outwardly. Focusing all of the accelerated water rearward increases forward thrust.

FIG. 2 provides an additional prospective view of improved propeller 100. This view is taken from the side and slightly behind the rear of the improved propeller 100. Housing 120 includes flared out forward edge 130, longitudinal housing portion 125, tapered portion 140, rear portion 150 and outer blades 160 are further illustrated in this view.

FIG. 3 is a rear prospective view of the improved propeller 100. FIG. 3 illustrates the housing 120 having a tapered portion 140, a rear portion 150 and outer blades 160. Also shown is hub 300 and inner hub 310. Inner hub 310 slides over the shaft of an outboard drive unit (not shown). Preferably, a nut (not shown) secures the improved propeller 100 to the drive unit just as it does a conventional propeller.

In one embodiment, the tapered portion 140 reduces the diameter of the housing 120 down to the rear portion 150 so that the rear portion 150 has a cross sectional area that is less than the cross sectional area of the outside diameter of the inside blades 115 (FIG. 1) minus the cross sectional area of hub 300. The smaller cross sectional area of the rear portion 150 forces the water two accelerate through the rear portion 150.

FIG. 4 illustrates another embodiment of an improved propeller 400. Improved propeller 400 is similar to improved propeller 100. Improved propeller 400 includes a housing 405 having a flared out forward edge 410, a longitudinal housing portion 420, a tapered portion 430, outer blades 440, rear portion 450, and forward hub 460. These elements perform similar functions as their counter parts described above.

FIG. 5 illustrates that path of water 510 through, and around, improved propeller 400. Water 510 flows into the flared out forward edge 410. As described briefly above, flared out forward edge 410 forces more water 510 to contact with the blades then normally would contact the conventional blades. As the blades spin, the blades (not shown) force the water 510 rearward through housing 405. The water 510 a accelerates as it flows through tapered portion 430. Water is incompressible so as the water 510 is forced through rear portion 430 the water must accelerate. The accelerated water 510 b passes through the rear portion 450 and creates additional thrust. In addition, often the drive units exhausts the engine fumes near the propeller 110 (FIG. 1) and, as a result the exhaust gases are compressed in the tapered portion 430. The compressed exhaust fumes 515 exit along with the accelerated water 510 b and may cause enhanced performance. Water 510 a flowing around the outside of housing 405 contacts outer blades 440 to provide additional thrust. Increases in the speed of the boat, increases the volume of water flowing into the housing, and results in increases in the efficiency of the improved propeller.

FIG. 6 illustrates the path of water 610 when the improved propeller 400 is rotated in the reverse direction. Because of the reduced diameter at the housing 405, the amount of water 610 that would otherwise contact the propeller that is inside housing 405 is reduced. Outer blades 440 contact the water 610 and force water 610 a around housing 405 to provide additional reverse thrust.

FIG. 7 is yet another embodiment of an improved propeller/impeller 700. The improved impeller 700 includes a tapered housing 720, an impeller 710 that includes mounting hubs 730 and 740, and outer blades 750. The operation of the impeller 700 is similar to the operation of the improved propellers discussed in detail above.

FIG. 8 illustrates another exemplary embodiment of an improved propeller 800. The improved propeller 800 includes a inner propeller 810 having a plurality of blades 815. Secured to the propeller 810 is a housing 820. Housing 820 includes a flared out forward edge 830, a longitudinal housing portion 825, a tapered portion 840, and a rear portion 850. Tapered portion 840 may have a linear taper, as shown, a curved taper, or have any number of different shaped tapers that server to reduce the housing 820 from a first diameter to a second smaller diameter. Propeller 810 includes a forward hub 870 for fitting into a conventional outboard drive unit (not shown). The housing 820 and propeller 810 may have a unitary construction to form improved propeller 800. Unitary construction, as used herein, does not mean it is formed of one solid piece, bur rather may be formed of multiple pieces that are joined or fastened together. Improved propeller 810 may be formed from aluminum, stainless steel, plastic, a composite, combinations of these materials, or any other suitable material(s). In one embodiment the propeller 810 is a conventional propeller, and housing 820 is modified so that it can be secured to the conventional propeller 810. For example, housing 820 may include pockets (not shown) for receiving blades of a conventional propeller, housing 820 may be mechanically fastened or welded to the conventional propellers. Slight modifications to the conventional propeller for securing it to the housing 810 is contemplated. Rear portion 850 may flare outward, have a constant diameter, or even taper inward.

While the present invention has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. For example, the housing member may be integrally formed with, or secured to, a drive unit, and the propeller would rotate inside of the housing. Therefore, the invention, in its broader aspects, is not limited to the specific details, the representative apparatus, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant's general inventive concept. 

1. A propeller comprising: a housing secured to a plurality of blades; the blades secured to a hub for mounting the propeller to a watercraft; the housing at least partially enclosing the plurality of blades; the housing further having a front section and a tapered section; the front section having an inside diameter that is greater than an inside diameter of the tapered section.
 2. The propeller of claim 1 further comprising a flared forward edge on the leading portion of the front section, wherein at least part of the flared forward edge has an inside diameter that is greater than the inside diameter of the front section.
 3. The propeller of claim 1 wherein the housing further comprises a rear section.
 4. The propeller of claim 3 wherein the rear section tapers outward.
 5. The propeller of claim 3 wherein the rear section has a cross sectional area that is less than the cross sectional area of the outside diameter of the blades minus the cross sectional area of the hub.
 6. The propeller of claim 1 wherein the propeller is a unitary construction.
 7. The propeller of claim 1 wherein the tapered section has a linear taper.
 8. The propeller of claim 1 wherein the propeller has three blades.
 9. The propeller of claim 3 further comprising outer blades secured to the rear section.
 10. A housing for a propeller comprising: a longitudinal forward section and a tapered rear section; wherein the longitudinal forward section of the housing is configured to be secured to three or more propeller blades.
 11. The propeller of claim 10 wherein the housing further comprises pockets for receiving the three or more propeller blades.
 12. The propeller of claim 10 wherein the housing is welded to the three or more propeller blades.
 13. The propeller of claim 10 wherein the housing is mechanically fastened to the three or more propeller blades.
 14. A propeller comprising: a plurality of blades secured to a hub for mounting the propeller to a watercraft; a housing secured to the plurality of blades and at least partially enclosing the plurality of blades; the housing having a water inlet and a water outlet; and a tapered section connecting the water inlet to the water outlet so that the passageway of the water outlet is narrower than the passageway of the water inlet.
 15. The propeller of claim 14 wherein the water inlet comprises an outwardly flared forward edge.
 16. The propeller of claim 14 wherein the water outlet comprises a rear section.
 17. The propeller of claim 14 wherein the aft section of the tapered section has a cross sectional area that is less than the cross sectional area of the outside diameter of the blades minus the cross sectional area of the hub.
 18. The propeller of claim 14 wherein the rear section tapers outward.
 19. The propeller of claim 14 wherein the propeller is a unitary construction.
 20. The propeller of claim 14 wherein the tapered section has a linear taper.
 21. The propeller of claim 14 wherein the propeller has three blades.
 22. The propeller of claim 16 further comprising outer blades secured to the rear section.
 23. A propeller comprising: a plurality of blades; a housing secured to the plurality of blades; the housing having a first diameter and a second diameter, wherein the first diameter is upstream from the second diameter and the second diameter is less then the first diameter. 